The fee for the GIA Laboratory-Grown Diamond Quality Assessment is US$15 per carat, with a minimum fee of $15. Submissions that do not meet the minimum criteria for assessment will be charged a US$5 ...

Explore diamond history, research, quality factors, and more in the GIA Gem Encyclopedia.

Major rock units of the Neyshabur mine are divided into three groups: volcanic, subvolcanic intrusions, and hydrothermal breccia (Ghiasvand et al., 2017). Although the volcanic rocks of trachyte and ...

Shipley returned to the U.S. in 1929 and launched his “preliminary course in gemology” in Los Angeles on Sept. 16, 1930. In the years that followed, he covered thousands of miles in secondhand cars, ...

There is so much variety in natural diamond surfaces that, like snowflakes, no two diamonds are exactly alike. These differences can give us useful information about how diamonds react with fluids in ...

As part of this service, a gold bracelet measuring 8 inches in circumference and 1.25 inches wide and weighing 41 g was recently examined in the Carlsbad laboratory (figure 1). It was submitted as 14K ...

This 32” x 20” wall chart presents GIA’s system for classifying pearl quality according to the seven factors of size, shape, color, luster, surface, matching, and nacre.

Figure 1. A comparison of the Mohs hardness scale and the Knoop hardness scale, a micro-hardness test where a pyramidal diamond point is pressed into the polished surface of the sample with a known ...

The phrase “light performance” gets a lot of loose use in the diamond trade. Terms such as brightness, brilliance, fire and scintillation are defined by various organizations with both clear and vague ...

Small but bright, saltwater akoya pearls are famed for their white to cream color, mirror-like shine and attractive overtones. Freshwater pearls, on the other hand, are famed for their wide palette of ...

Asteriated synthetic rubies and sapphires were produced by Wiede’s Carbidwerk of Freyung, Germany, between the mid-1950s and the end of the 1970s. The rough crystals were grown slowly through a ...

Your name or store info is removed so grading is completely unbiased. Every pearl or pearl strand, whether from a local jeweler or a globally recognized brand, is evaluated using the same rigorous, ...